Tuned microcavity color OLED display

ABSTRACT

A color OLED display having at least three different colored microcavity pixels including a light-reflective structure and a semitransparent structure comprising an array of light-emitting microcavity pixels each having one or more common organic light-emitting layers, said light-emitting layer(s) having first, second, and third light-emitting materials that produce different light spectra. The first light-emitting material producing light has a first spectrum portion that is substantially contained within a first color of the array, the second light-emitting material producing light has a second spectrum portion that is substantially contained within a second color that is different from the first color, and the third light-emitting material producing light has a third spectrum portion that is substantially contained within a third color that is different from the first and second colors.

CROSS REFERENCE TO RELATED APPLICATIONS

Reference is made to commonly assigned U.S. patent application Ser. No.10/820,570 filed Apr. 8, 2004, entitled “OLED With Color Change Media”by Michael L. Boroson, et al.; commonly assigned U.S. patent applicationSer. No. 10/820,592 filed Apr. 8, 2004, entitled “OLED Device HavingMicrocavity Subpixels and Color Filter Elements” by Dustin L. Winters;commonly assigned U.S. patent application Ser. No. 10/819,697 filed Apr.7, 2004, entitled “Color OLED With Added Color Gamut Pixels” by MichaelL. Boroson, et al.; commonly assigned U.S. patent application Ser. No.10/643,837 filed Aug. 19, 2003, entitled “OLED Device Having MicrocavityGamut Subpixels and a Within Gamut Subpixel” by Dustin L. Winters, etal.; commonly assigned U.S. patent application Ser. No. 10/762,675 filedJan. 22, 2004, entitled “Green Light-Emitting Microcavity OLED DeviceUsing a Yellow Color Filter Element” by Dustin L. Winters, et al.;commonly assigned U.S. patent application Ser. No. 10/680,758 filed Oct.7, 2003, entitled “White-Emitting Microcavity OLED Device” by Yuan-ShengTyan, et al.; commonly assigned U.S. patent application Ser. No.10/346,424 (filed Jan. 17, 2003, entitled “Microcavity OLED Devices” byYuan-Sheng Tyan, et al.; commonly assigned U.S. patent application Ser.No. 10/356,271 (filed Jan. 31, 2003, entitled “Color OLED Display WithImproved Emission” by Yuan-Sheng Tyan, et al.; and commonly assignedU.S. patent application Ser. No. 10/368,513 filed Feb. 18, 2003,entitled “Tuned Microcavity Color OLED Display” by Yuan-Sheng Tyan, etal., the disclosures of which are herein incorporated by reference.

FIELD OF THE INVENTION

The present invention relates to an improved tuned microcavity colorOLED display device.

BACKGROUND OF THE INVENTION

An organic light-emitting diode device, also called an OLED device,commonly includes a substrate, an anode, a hole-transporting layer madeof an organic compound, an organic luminescent layer with suitabledopants, an organic electron-transporting layer, and a cathode. OLEDdevices are attractive because of their low driving voltage, highluminance, wide-angle viewing and capability for full color flatemission displays. Tang et al. described this multilayer OLED device intheir U.S. Pat. Nos. 4,769,292 and 4,885,211.

Full color OLED devices are also known in the art. Typical full colorOLED devices are constructed of three different color pixels that arered, green, and blue in color. Such an arrangement is known as an RGBdesign. An example of an RGB design is disclosed in U.S. Pat. No.6,281,634. Full color organic electroluminescent (EL) devices have alsorecently been described that are constructed of four different colorpixels that are red, green, blue, and white. Such an arrangement isknown as an RGBW design. An example of an RGBW device is disclosed incommonly assigned U.S. Patent Application Publication 2002/0186214 A1.In an RGBW device, high efficiency white-emitting pixels are used todisplay a portion of the digital image content. This results in improvedpower consumption relative to an RGB device constructed of similar OLEDmaterials.

A white-emitting EL layer can be used to form a multicolor device. Eachpixel is coupled with a color filter element as part of a color filterarray (CFA) to achieve a pixilated multicolor display. The organic ELlayer is common to all pixels and the final color as perceived by theviewer is dictated by that pixel's corresponding color filter element.Therefore a multicolor or RGB device can be produced without requiringany patterning of the organic EL layers. An example of a white CFAtop-emitting device is shown in U.S. Pat. No. 6,392,340. Other examplesof white light-emitting OLED devices are disclosed in U.S. Pat. No.5,683,823, JP 07-142169, and U.S. Pat. No. 5,405,709.

Kido et al., in Science, Vol. 267, p. 1332 (1995) and in Appl. Phys.Lett., Vol. 64, p. 815 (1994), report a white light-producing OLEDdevice. In this device, three emitter layers with different carriertransport properties, each emitting blue, green, or red light, are usedto produce white light. Littman et al. in U.S. Pat. No. 5,405,709disclose another white emitting device, which is capable of emittingwhite light in response to hole-electron recombination, and comprises afluorescent material in a visible light range from bluish green to red.Recently, Deshpande et al., in Appl. Phys. Lett., Vol. 75, p. 888(1999), published a white OLED device using red, blue, and greenluminescent layers separated by a hole-blocking layer.

A problem in the application of white OLED devices, when used with colorfilters, is that the intensity of one or more of the red, green, andblue components of the emission spectrum is frequently lower thandesired. Therefore, passing the white light from the OLED through thered, green, and blue color filters provides light with a lowerefficiency than desired. Consequently, the power that is required toproduce a white color in the display by mixing red, green, and bluelight can also be higher than desired.

One way of improving the efficiency of an OLED device is the use of amicrocavity structure. A reflector and a semitransparent reflectorfunction, with the layers between them, to form a microcavity. Thelayers between the reflectors can be adjusted in thickness andrefractive index so that the resulting optical microcavity resonates ata desired wavelength. Examples of microcavity structures are shown inU.S. Pat. Nos. 5,405,710; 5,554,911; 6,406,801; 5,780,174; and JP11288786.

Microcavity devices, however, have a known problem in that colordistortion can occur when viewed at varying angles from the normalviewing angle. This effect is described in U.S. Pat. No. 5,780,174.Microcavity devices are characteristically directional; the emissionintensity also varies with viewing angle. See, for example, N. Takada,T. Tsutsui, and S. Saito Appl. Phys. Lett. Vol. 63, p. 2032 (1993)“Control of emission characteristics in organic thin-filmelectroluminescent diodes using an optical-microcavity structure”.Therefore, an OLED device using microcavity structures having reduceddependence of perceived color on the angle of view is desired.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to produce anefficient color OLED display with reduced color dependence on viewingangle.

This object is achieved by a color OLED display having at least threedifferent colored microcavity pixels including a light-reflectivestructure and a semitransparent structure, comprising:

a) an array of light-emitting microcavity pixels each having one or morecommon organic light-emitting layers, said light-emitting layer(s)having first, second, and third light-emitting materials that producedifferent light spectra, the first light-emitting material producinglight having a first spectrum portion that is substantially containedwithin a first color of the array, the second light-emitting materialproducing light having a second spectrum portion that is substantiallycontained within a second color that is different from the first color,and third light-emitting material producing light having a thirdspectrum portion that is substantially contained within a third colorthat is different from the first and second colors; and

b) each different colored pixel being tuned to produce light in one ofthe three different colors whereby the first, second, and thirddifferent colors are produced by the OLED display.

ADVANTAGES

It is an advantage of this invention that it provides better colorconsistency, that is, less color distortion, when viewed at an angle. Itis a further advantage of this invention that it provides a better colorgamut than prior art devices. It is a further advantage of thisinvention that it provides for a device with improved lifetime. It is afurther advantage of this invention that it provides an emission peakfor each tunable microcavity.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a single light-emitting microcavitypixel of a color OLED display according to this invention;

FIG. 2 is a cross-sectional view of an array of light-emittingmicrocavity pixels of a color OLED display according to this invention;

FIG. 3 a is an emission spectrum of a comparative white light-emittingOLED device;

FIG. 3 b is a 1931 CIE x,y-chromaticity diagram showing the color gamutmodeled with the above comparative white light-emitting OLED device;

FIG. 4 a is an emission spectrum of a first white light-emitting OLEDdevice according to this invention;

FIG. 4 b is a 1931 CIE x,y-chromaticity diagram showing the color gamutmodeled with the above first white light-emitting OLED device;

FIG. 5 a is an emission spectrum of a second white light-emitting OLEDdevice according to this invention;

FIG. 5 b is a 1931 CIE x,y-chromaticity diagram showing the color gamutmodeled with the above second white light-emitting OLED device;

FIG. 6 a is an emission spectrum of a third white light-emitting OLEDdevice according to this invention; and

FIG. 6 b is a 1931 CIE x,y-chromaticity diagram showing the color gamutmodeled with the above third white light-emitting OLED device.

Since device feature dimensions such as layer thicknesses are frequentlyin submicrometer ranges, the drawings are scaled for ease ofvisualization rather than dimensional accuracy.

DETAILED DESCRIPTION OF THE INVENTION

The term “OLED device” or “organic light-emitting display” is used inits art-recognized meaning of a display device comprising organiclight-emitting diodes as pixels. A color OLED device emits light of atleast one color. The term “multicolor” is employed to describe a displaypanel that is capable of emitting light of a different hue in differentareas. In particular, it is employed to describe a display panel that iscapable of displaying images of different colors. These areas are notnecessarily contiguous. The term “full color” is commonly employed todescribe multicolor display panels that are capable of emitting in thered, green, and blue regions of the visible spectrum and displayingimages in any combination of hues. The red, green, and blue colorsconstitute the three primary colors from which all other colors can beproduced by appropriate mixing. However, the use of additional colors toextend the color gamut of the device is possible. The term “hue” refersto the intensity profile of light emission within the visible spectrum,with different hues exhibiting visually discernible differences incolor. The term “pixel” is employed in its art-recognized usage todesignate an area of a display panel that can be stimulated to emitlight independently of other areas. It is recognized that in full colorsystems, several pixels of different colors will be used together toproduce a broad range of colors, and a viewer can term such a group asingle pixel. For the purposes of this discussion, such a group will beconsidered several different colored pixels.

In accordance with this disclosure, broadband emission is light that hassignificant components in multiple portions of the visible spectrum, forexample, blue and green. Broadband emission can also include thesituation where light is emitted in the red, green, and blue portions ofthe spectrum in order to produce white light. White light is that lightthat is perceived by a user as having a white color, or light that hasan emission spectrum sufficient to be used in combination with colorfilters to produce a multicolor or full color display. Although CIEx,CIEy coordinates of about 0.33, 0.33 can be ideal in some circumstances,the actual coordinates can vary significantly and still be very useful.The term substantially contained within the red portion of the visiblespectrum refers to that light such that the emission maximum and fullwidth at half maximum is contained between 560 nm and 700 nm. The termsubstantially contained within the green portion of the visible spectrumrefers to that light such that the emission maximum and full width athalf maximum is contained between 490 nm and 580 nm. The termsubstantially contained within the blue portion of the visible spectrumrefers to that light such that the emission maximum and full width athalf maximum is contained between 400 nm and 490 nm. Red light-emittingmaterials in accordance with this invention are referred to as havingnarrow band emission, meaning the full width at half maximum is between5 nm and 90 nm. Green light-emitting materials in accordance with thisinvention are referred to as having narrow band emission, meaning thefull width at half maximum is between 5 nm and 70 nm. Bluelight-emitting materials in accordance with this invention are referredto as having narrow band emission, meaning the full width at halfmaximum is between 5 nm 25 nm. By emission maximum, it is meant awavelength of maximum emission, also called λ_(max) (e.g., λ_(max) 105in FIG. 3 a). By full width at half maximum, it is meant the width of agiven emission peak at one-half its maximum value, e.g., full width athalf maximum 110 in FIG. 3 a.

The present invention can be employed in most OLED deviceconfigurations. These include very simple structures comprising a singleanode and cathode, to more complex devices including passive matrixdisplays comprised of orthogonal arrays of anodes and cathodes to formpixels, and active-matrix displays where each pixel is controlledindependently, for example, with thin film transistors (TFTs). OLEDdevices of this invention can operate under forward biasing and so canfunction under Direct Current (DC) mode. It is sometimes advantageous toapply a reverse bias, e.g. in an alternating current (AC) mode. The OLEDtypically does not emit light under reverse bias, but significantstability enhancements have been demonstrated, as described in U.S. Pat.No. 5,552,678.

Turning now to FIG. 1, there is shown a cross-sectional view of a singlelight-emitting microcavity pixel 10 of a light-emitting color OLEDdisplay according to the present invention. Microcavity pixel 10 is abottom-emitting device, however, alternate embodiments where themicrocavity pixel is a top-emitting device are also possible and areenvisioned as being within the scope of the present invention. Abottom-emitting device is a device where the substrate is between thelight-emitting layers and the viewer when viewed such that light passesthrough the substrate and the viewer views the device from the side ofthe substrate. A top-emitting device is a device where thelight-emitting layers are between the substrate and the viewer and isviewed from the opposite side of the substrate compared to abottom-emitting device. The OLED device includes at a minimum asubstrate 20, a semitransparent reflector 25, a reflector 90 spaced fromsemitransparent reflector 25, a first light-emitting layer 45, a secondlight-emitting layer 50, and a third light-emitting layer 55. Eachlight-emitting layer includes respective light-emitting material that isdesigned to produce different light spectra in response to hole-electronrecombination. The first light-emitting layer material, in firstlight-emitting layer 45, produces light having a first spectrum portionthat is substantially contained within a first color, e.g. red. Thesecond light-emitting layer material, in second light-emitting layer 50,produces light having a second spectrum portion that is substantiallycontained within a second color different from the first color, e.g.green. The third light-emitting layer material, in third light-emittinglayer 55, produces light having a third spectrum portion that issubstantially contained within a third color that is different from thefirst and second colors, e.g. blue. Microcavity pixel 10 includes amicrocavity structure that is tuned to produce light in one of the threecolors of the light-emitting layers 45, 50, and 55. The pixel can alsoinclude cavity spacer layer 30, a hole-injecting layer 35, ahole-transporting layer 40, an electron-transporting layer 60, and anelectron-injecting layer 65. Hole-injecting layer 35, hole-transportinglayer 40, light-emitting layers 45, 50, and 55, electron-transportinglayer 60, and electron-injecting layer 65 comprise organic EL element 70that is disposed between semitransparent reflector 25 and reflector 90.These components will be described in more detail.

Microcavity pixel 10 is arranged such that light produced in the organicEL element 70 passes through semitransparent reflector 25 and substrate20. This configuration where light travels through the substrate isknown as a bottom-emitting device. In this configuration, substrate 20is preferably highly transparent and is constructed of a material suchas glass or plastic. Alternately, the device could be fabricated withthe reflector between the substrate and the organic EL medium. Thisalternate configuration is known as a top-emitting device. In atop-emitting device, light does not pass through the substrate and thesubstrate can therefore be optionally opaque. This configuration enablesthe use of a large variety of substrates. Example substrates that can beused with a top-emitting configuration include semi-conductors, metallicfoils, and ceramics.

Substrate 20 can be rigid or flexible and can be processed as separateindividual pieces, such as sheets or wafers, or as a continuous roll.Substrate 20 can be a homogeneous mixture of materials, a composite ofmaterials, or multiple layers of materials. The substrate can furtherinclude active matrix circuitry (not shown) to drive the microcavitydevice.

Light produced in the organic EL element 70 exits the device through thesemitransparent reflector 25, which is designed to be partiallytransmitting and partially reflecting at the wavelength of interest.Semitransparent reflector 25 could be constructed of a thin metal layersuch as Ag or an alloy of Ag, which is preferably between 5 nm and 35 nmin thickness. Ag is a preferred metal since, when formed in a thinlayer, it is reflective and transparent with low absorbance. Othermetals such as Au or Al can also be made to work. The cavity spacer 12is constructed of a transparent material such as ITO, IZO, or the like.In this example, the cavity spacer layer also serves as the firstelectrode for the OLED device. The first electrode is commonlyconfigured as the anode. However, the practice of this invention is notlimited to this configuration, and can instead have a cathode as thefirst electrode. For the purposes of this discussion, the firstelectrode is considered the anode. While the cavity spacer layer isshown as a single layer, it can alternately be composed of severallayers of different materials. The reflector 25 is preferablyconstructed of a highly reflective metal including, but not limited to,Al, Ag, Au, and alloys thereof. In this example, the reflector alsoserves as the second electrode for the OLED device. The second electrodeis commonly configured as the cathode. However, the practice of thisinvention is not limited to this configuration, and can instead have ananode as the second electrode. For the purposes of this discussion, thesecond electrode is considered the cathode.

Microcavity pixel 10 is an example embodiment of a microcavity devicestructure. Several variations are known in the art and can also beapplied to the present invention. For example, the semitransparentreflector could be constructed from a quarter wave stack (QWS) ofseveral alternating layers of transparent materials having differentrefractive indexes. An example of an OLED microcavity device with a QWSis shown in U.S. Pat. No. 5,405,710. In another alternate embodiment,the cavity spacer layer could alternately be placed between thereflector and the organic EL medium, or it could be eliminated entirely.In either of these cases, the semitransparent reflector would then needto serve as the first electrode for the OLED device.

While not always necessary, it is often useful that a hole-injectinglayer 35 be formed over the anode in an organic light-emitting display.The hole-injecting material can serve to improve the film formationproperty of subsequent organic layers and to facilitate injection ofholes into the hole-transporting layer. Suitable materials for use inhole-injecting layer 35 include, but are not limited to, porphyriniccompounds as described in U.S. Pat. No. 4,720,432, plasma-depositedfluorocarbon polymers as described in U.S. Pat. No. 6,208,075, andinorganic oxides including vanadium oxide (VOx), molybdenum oxide(MoOx), nickel oxide (NiOx), etc. Alternative hole-injecting materialsreportedly useful in organic EL devices are described in EP 0 891 121 A1and EP 1 029 909 A1.

While not always necessary, it is often useful that a hole-transportinglayer 40 be formed and disposed over the anode. Desiredhole-transporting materials can be deposited by any suitable way such asevaporation, sputtering, chemical vapor deposition, electrochemicalmeans, thermal transfer, or laser thermal transfer from a donormaterial. Hole-transporting materials useful in hole-transporting layer40 are well known to include compounds such as an aromatic tertiaryamine, where the latter is understood to be a compound containing atleast one trivalent nitrogen atom that is bonded only to carbon atoms,at least one of which is a member of an aromatic ring. In one form thearomatic tertiary amine can be an arylamine, such as a monoarylamine,diarylamine, triarylamine, or a polymeric arylamine. Exemplary monomerictriarylamines are illustrated by Klupfel et al. in U.S. Pat. No.3,180,730. Other suitable triarylamines substituted with one or morevinyl radicals and/or comprising at least one active hydrogen-containinggroup are disclosed by Brantley et al. in U.S. Pat. Nos. 3,567,450 and3,658,520.

A more preferred class of aromatic tertiary amines are those whichinclude at least two aromatic tertiary amine moieties as described inU.S. Pat. Nos. 4,720,432 and 5,061,569. Such compounds include thoserepresented by structural Formula A

wherein:

-   -   Q₁ and Q₂ are independently selected aromatic tertiary amine        moieties; and    -   G is a linking group such as an arylene, cycloalkylene, or        alkylene group of a carbon to carbon bond.

In one embodiment, at least one of Q₁ or Q₂ contains a polycyclic fusedring structure, e.g., a naphthalene. When G is an aryl group, it isconveniently a phenylene, biphenylene, or naphthalene moiety.

A useful class of triarylamines satisfying structural Formula A andcontaining two triarylamine moieties is represented by structuralFormula B

where:

R₁ and R₂ each independently represent a hydrogen atom, an aryl group,or an alkyl group or R₁ and R₂ together represent the atoms completing acycloalkyl group; and

-   -   R₃ and R₄ each independently represent an aryl group, which is        in turn substituted with a diaryl substituted amino group, as        indicated by structural Formula C        wherein R₅ and R₆ are independently selected aryl groups. In one        embodiment, at least one of R₅ or R₆ contains a polycyclic fused        ring structure, e.g., a naphthalene.

Another class of aromatic tertiary amines are the tetraaryldiamines.Desirable tetraaryldiamines include two diarylamino groups, such asindicated by Formula C, linked through an arylene group. Usefultetraaryldiamines include those represented by Formula D

wherein:

-   -   each Are is an independently selected arylene group, such as a        phenylene or anthracene moiety;    -   n is an integer of from 1 to 4; and    -   Ar, R₇, R₈, and R₉ are independently selected aryl groups.

In a typical embodiment, at least one of Ar, R₇, R₈, and R₉ is apolycyclic fused ring structure, e.g., a naphthalene.

The various alkyl, alkylene, aryl, and arylene moieties of the foregoingstructural Formulae A, B, C, D, can each in turn be substituted. Typicalsubstituents include alkyl groups, alkoxy groups, aryl groups, aryloxygroups, and halogens such as fluoride, chloride, and bromide. Thevarious alkyl and alkylene moieties typically contain from 1 to about 6carbon atoms. The cycloalkyl moieties can contain from 3 to about 10carbon atoms, but typically contain five, six, or seven carbonatoms—e.g., cyclopentyl, cyclohexyl, and cycloheptyl ring structures.The aryl and arylene moieties are usually phenyl and phenylene moieties.

The hole-transporting layer in an OLED device can be formed of a singleor a mixture of aromatic tertiary amine compounds. Specifically, one canemploy a triarylamine, such as a triarylamine satisfying the Formula B,in combination with a tetraaryldiamine, such as indicated by Formula D.When a triarylamine is employed in combination with a tetraaryldiamine,the latter is positioned as a layer interposed between the triarylamineand the electron-injecting and transporting layer. Illustrative ofuseful aromatic tertiary amines are the following:

-   -   1,1-Bis(4-di-p-tolylaminophenyl)cyclohexane;    -   1,1-Bis(4-di-p-tolylaminophenyl)-4-phenylcyclohexane;    -   N,N,N′,N′-tetraphenyl-4,4′″-diamino-1,1′:4′,1″:4″,1′″-quaterphenyl;    -   Bis(4-dimethylamino-2-methylphenyl)phenylmethane;    -   1,4-bis[2-[4-[N,N-di(p-tolyl)amino]phenyl]vinyl]benzene        (BDTAPVB);    -   N,N,N′,N′-Tetra-p-tolyl-4,4′-diaminobiphenyl;    -   N,N,N′,N′-Tetraphenyl-4,4′-diaminobiphenyl;    -   N,N,N′,N′-tetra-1-naphthyl-4,4′-diaminobiphenyl;    -   N,N,N′,N′-tetra-2-naphthyl-4,4′-diaminobiphenyl;    -   N-Phenylcarbazole;    -   4,4′-Bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB);    -   4,4′-Bis[N-(1-naphthyl)-N-(2-naphthyl)amino]biphenyl (TNB);    -   4,4′-Bis[N-(1-naphthyl)-N-phenylamino]p-terphenyl;    -   4,4′-Bis[N-(2-naphthyl)-N-phenylamino]biphenyl;    -   4,4′-Bis[N-(3-acenaphthenyl)-N-phenylamino]biphenyl;    -   1,5-Bis[N-(1-naphthyl)-N-phenylamino]naphthalene;    -   4,4′-Bis[N-(9-anthryl)-N-phenylamino]biphenyl;    -   4,4′-Bis[N-(1-anthryl)-N-phenylamino]-p-terphenyl;    -   4,4′-Bis[N-(2-phenanthryl)-N-phenylamino]biphenyl;    -   4,4′-Bis[N-(8-fluoranthenyl)-N-phenylamino]biphenyl;    -   4,4′-Bis[N-(2-pyrenyl)-N-phenylamino]biphenyl;    -   4,4′-Bis[N-(2-naphthacenyl)-N-phenylamino]biphenyl;    -   4,4′-Bis[N-(2-perylenyl)-N-phenylamino]biphenyl;    -   4,4′-Bis[N-(1-coronenyl)-N-phenylamino]biphenyl;    -   2,6-Bis(di-p-tolylamino)naphthalene;    -   2,6-Bis[di-(1-naphthyl)amino]naphthalene;    -   2,6-Bis[N-(1-naphthyl)-N-(2-naphthyl)amino]naphthalene;    -   N,N,N′,N′-Tetra(2-naphthyl)-4,4″-diamino-p-terphenyl;    -   4,4′-Bis{N-phenyl-N-[4-(1-naphthyl)-phenyl]amino}biphenyl;    -   2,6-Bis[N,N-di(2-naphthyl)amino]fluorene;    -   4,4′,4″-tris[(3-methylphenyl)phenylamino]triphenylamine        (MTDATA); and    -   4,4′-Bis[N-(3-methylphenyl)-N-phenylamino]biphenyl (TPD).

Another class of useful hole-transporting materials includes polycyclicaromatic compounds as described in EP 1 009 041. Some hole-injectingmaterials described in EP 0 891 121 A1 and EP 1 029 909 A1 can also makeuseful hole-transporting materials. In addition, polymerichole-transporting materials can be used such as poly(N-vinylcarbazole)(PVK), polythiophenes, polypyrrole, polyaniline, and copolymers such aspoly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) also calledPEDOT/PSS.

Light-emitting layers 45, 50, and 55 produce light in response tohole-electron recombination. A light-emitting layer is commonly disposedover hole-transporting layer 40 in an OLED display. Desired organiclight-emitting materials can be deposited by any suitable way such asevaporation, sputtering, chemical vapor deposition, electrochemicalmeans, or radiation thermal transfer from a donor material. Usefulorganic light-emitting materials are well known. As more fully describedin U.S. Pat. Nos. 4,769,292 and 5,935,721, the light-emitting layers ofthe organic EL element comprise a luminescent or fluorescent materialwhere electroluminescence is produced as a result of electron-hole pairrecombination in this region. A light-emitting layer can be comprised ofa single material, but more commonly includes a host doped with a guestcompound or dopant where light emission comes primarily from the dopant.First light-emitting layer 45 includes a first host, secondlight-emitting layer 50 includes a second host, and third light-emittinglayer 55 includes a third host. Any two of the hosts, e.g. the secondand third hosts, or all of the hosts, can be the same material. Any ofthe hosts can comprise a single host material or a mixture of hostmaterials. The dopant is selected to produce colored light having aparticular spectrum. First light-emitting layer 45 includes alight-emitting compound of the first color, e.g. a red light-emittingcompound. Second light-emitting layer 50 includes a light-emittingcompound of the second color, e.g. a green light-emitting compound.Third light-emitting layer 55 includes a light-emitting compound of thethird color, e.g. a blue-light-emitting compound. The practice of thisinvention is not restricted to this ordering of layers. For example,second light-emitting layer 50 can include a blue-light-emittingcompound, and third light-emitting layer 55 can include agreen-light-emitting compound. The host materials in the light-emittinglayers can be an electron-transporting material, as defined below, ahole-transporting material, as defined above, or another material thatsupports hole-electron recombination. The dopant is usually chosen fromhighly fluorescent dyes, but phosphorescent compounds, e.g., transitionmetal complexes as described in WO 98/55561, WO 00/18851, WO 00/57676,and WO 00/70655 are also potentially useful. Dopants are typicallycoated as 0.01 to 10% by weight into the host material. Lanthanideemitters, for example as set forth in WO 98/58037 and WO 00/32718, areuseful. In this invention, however, any light-emitting material mustsatisfy the emission maximum and full width, half maximum requirementsas set forth previously.

The host and emitting materials can be small nonpolymeric molecules orpolymeric materials including polyfluorenes and polyvinylarylenes, e.g.,poly(p-phenylenevinylene), PPV. In the case of polymers, small moleculeemitting materials can be molecularly dispersed into a polymeric host,or the emitting materials can be added by copolymerizing a minorconstituent into a host polymer.

An important relationship for choosing an emitting material is acomparison of the bandgap potential, which is defined as the energydifference between the highest occupied molecular orbital and the lowestunoccupied molecular orbital of the molecule. For efficient energytransfer from the host to the emitting material, a necessary conditionis that the bandgap of the dopant is smaller than that of the hostmaterial. For phosphorescent emitters (including materials that emitfrom a triplet excited state, i.e., so-called “triplet emitters”) it isalso important that the triplet energy level of the host be high enoughto enable energy transfer from host to emitting material.

Host and emitting molecules known to be of use include, but are notlimited to, those disclosed in U.S. Pat. Nos. 4,768,292; 5,141,671;5,150,006; 5,151,629; 5,294,870; 5,405,709; 5,484,922; 5,593,788;5,645,948; 5,683,823; 5,755,999; 5,928,802; 5,935,720; 5,935,721; and6,020,078.

Metal complexes of 8-hydroxyquinoline and similar derivatives (FormulaE) constitute one class of useful host materials capable of supportingelectroluminescence, and are particularly suitable for light emission ofwavelengths longer than 500 nm, e.g., green, yellow, orange, and red.

wherein:

-   -   M represents a metal;    -   n is an integer of from 1 to 3; and    -   Z independently in each occurrence represents the atoms        completing a nucleus having at least two fused aromatic rings.

From the foregoing it is apparent that the metal can be a monovalent,divalent, or trivalent metal. The metal can, for example, be an alkalimetal, such as lithium, sodium, or potassium; an alkaline earth metal,such as magnesium or calcium; or an earth metal, such as boron oraluminum. Generally any monovalent, divalent, or trivalent metal knownto be a useful chelating metal can be employed.

Z completes a heterocyclic nucleus containing at least two fusedaromatic rings, at least one of which is an azole or azine ring.Additional rings, including both aliphatic and aromatic rings, can befused with the two required rings, if required. To avoid addingmolecular bulk without improving on function the number of ring atoms isusually maintained at 18 or less.

Illustrative of useful chelated oxinoid compounds are the following:

-   -   CO-1: Aluminum trisoxine [alias,        tris(8-quinolinolato)aluminum(III)]    -   CO-2: Magnesium bisoxine [alias,        bis(8-quinolinolato)magnesium(II)]    -   CO-3: Bis[benzo{f}-8-quinolinolato]zinc (II)    -   CO-4:        Bis(2-methyl-8-quinolinolato)aluminum(III)-μ-oxo-bis(2-methyl-8-quinolinolato)        aluminum(III)    -   CO-5: Indium trisoxine [alias, tris(8-quinolinolato)indium]    -   CO-6: Aluminum tris(5-methyloxine) [alias,        tris(5-methyl-8-quinolinolato) aluminum(III)]    -   CO-7: Lithium oxine [alias, (8-quinolinolato)lithium(I)]    -   CO-8: Gallium oxine [alias, tris(8-quinolinolato)gallium(III)];        and    -   CO-9: Zirconium oxine [alias,        tetra(8-quinolinolato)zirconium(IV)].

The host material in one or more of the light-emitting layers of thisinvention can be an anthracene derivative having hydrocarbon orsubstituted hydrocarbon substituents at the 9 and 10 positions. Forexample, derivatives of 9,10-di-(2-naphthyl)anthracene (Formula F)constitute one class of useful host materials capable of supportingelectroluminescence, and are particularly suitable for light emission ofwavelengths longer than 400 nm, e.g., blue, green, yellow, orange orred.

wherein R¹, R₂, R³, R⁴, R⁵, and R⁶ represent one or more substituents oneach ring where each substituent is individually selected from thefollowing groups:

-   -   Group 1: hydrogen, or alkyl of from 1 to 24 carbon atoms;    -   Group 2: aryl or substituted aryl of from 5 to 20 carbon atoms;    -   Group 3: carbon atoms from 4 to 24 necessary to complete a fused        aromatic ring of anthracenyl, pyrenyl, or perylenyl;    -   Group 4: heteroaryl or substituted heteroaryl of from 5 to 24        carbon atoms as necessary to complete a fused heteroaromatic        ring of furyl, thienyl, pyridyl, quinolinyl or other        heterocyclic systems;    -   Group 5: alkoxylamino, alkylamino, or arylamino of from 1 to 24        carbon atoms; and    -   Group 6: fluorine, chlorine, bromine or cyano.

The monoanthracene derivative of Formula (I) is also a useful hostmaterial capable of supporting electroluminescence, and are particularlysuitable for light emission of wavelengths longer than 400 nm, e.g.,blue, green, yellow, orange or red. Anthracene derivatives of Formula(I) is described in commonly assigned U.S. patent application Ser. No.10/693,121 filed Oct. 24, 2003 by Lelia Cosimbescu et al., entitled“Electroluminescent Device With Anthracene Derivative Host”, thedisclosure of which is herein incorporated by reference,

wherein:

-   -   R₁-R₈ are H; and    -   R₉ is a naphthyl group containing no fused rings with aliphatic        carbon ring members; provided that R₉ and R₁₀ are not the same,        and are free of amines and sulfur compounds. Suitably, R₉ is a        substituted naphthyl group with one or more further fused rings        such that it forms a fused aromatic ring system, including a        phenanthryl, pyrenyl, fluoranthene, perylene, or substituted        with one or more substituents including fluorine, cyano group,        hydroxy, alkyl, alkoxy, aryloxy, aryl, a heterocyclic oxy group,        carboxy, trimethylsilyl group, or an unsubstituted naphthyl        group of two fused rings. Conveniently, R₉ is 2-naphthyl, or        1-naphthyl substituted or unsubstituted in the para position;        and    -   R₁₀ is a biphenyl group having no fused rings with aliphatic        carbon ring members. Suitably R₁₀ is a substituted biphenyl        group, such that is forms a fused aromatic ring system including        but not limited to a naphthyl, phenanthryl, perylene, or        substituted with one or more substituents including fluorine,        cyano group, hydroxy, alkyl, alkoxy, aryloxy, aryl, a        heterocyclic oxy group, carboxy, trimethylsilyl group, or an        unsubstituted biphenyl group. Conveniently, R₁₀ is 4-biphenyl,        3-biphenyl unsubstituted or substituted with another phenyl ring        without fused rings to form a terphenyl ring system, or        2-biphenyl. Particularly useful is        9-(2-naphthyl)-10-(4-biphenyl)anthracene.

Another useful class of anthracene derivatives is represented by generalformula (II)A 1--L--A 2  (II)wherein A 1 and A 2 each represent a substituted or unsubstitutedmonophenylanthryl group or a substituted or unsubstituteddiphenylanthryl group and can be the same with or different from eachother and L represents a single bond or a divalent linking group.

Another useful class of anthracene derivatives is represented by generalformula (III)A 3--An--A 4  (III)wherein An represents a substituted or unsubstituted divalent anthraceneresidue group, A 3 and A 4 each represent a substituted or unsubstitutedmonovalent condensed aromatic ring group or a substituted orunsubstituted non-condensed ring aryl group having 6 or more carbonatoms and can be the same with or different from each other.

Asymmetric anthracene derivatives as disclosed in U.S. Pat. No.6,465,115 and WO 2004/018587, are useful hosts and these compounds arerepresented by general formulas (IV) and (V) shown below, alone or as acomponent in a mixture

wherein:

-   -   Ar is an (un)substituted condensed aromatic group of 10-50        nuclear carbon atoms;    -   Ar′ is an (un)substituted aromatic group of 6-50 nuclear carbon        atoms;    -   X is an (un)substituted aromatic group of 6-50 nuclear carbon        atoms, (un)substituted aromatic heterocyclic group of 5-50        nuclear carbon atoms, (un)substituted alkyl group of 1-50 carbon        atoms, (un)substituted alkoxy group of 1-50 carbon atoms,        (un)substituted aralkyl group of 6-50 carbon atoms,        (un)substituted aryloxy group of 5-50 nuclear carbon atoms,        (un)substituted arylthio group of 5-50 nuclear carbon atoms,        (un)substituted alkoxycarbonyl group of 1-50 carbon atoms,        carboxy group, halogen atom, cyano group, nitro group, or        hydroxy group;    -   a, b, and c are whole numbers of 0-4; and n is a whole number of        1-3;    -   and when n is 2 or more, the formula inside the parenthesis        shown below can be the same or different

Furthermore, the present invention provides anthracene derivativesrepresented by general formula (V) shown below

wherein:

-   -   Ar is an (un)substituted condensed aromatic group of 10-50        nuclear carbon atoms;    -   Ar′ is an (un)substituted aromatic group of 6-50 nuclear carbon        atoms;    -   X is an (un)substituted aromatic group of 6-50 nuclear carbon        atoms, (un)substituted aromatic heterocyclic group of 5-50        nuclear carbon atoms, (un)substituted alkyl group of 1-50 carbon        atoms, (un)substituted alkoxy group of 1-50 carbon atoms,        (un)substituted aralkyl group of 6-50 carbon atoms,        (un)substituted aryloxy group of 5-50 nuclear carbon atoms,        (un)substituted arylthio group of 5-50 nuclear carbon atoms,        (un)substituted alkoxycarbonyl group of 1-50 carbon atoms,        carboxy group, halogen atom, cyano group, nitro group, or        hydroxy group;    -   a, b, and c are whole numbers of 0-4; and n is a whole number of        1-3; and    -   when n is 2 or more, the formula inside the parenthesis shown        below can be the same or different        Specific examples of useful anthracene materials for use in a        light-emitting layer include

Benzazole derivatives (Formula G) constitute another class of usefulhost materials capable of supporting electroluminescence, and areparticularly suitable for light emission of wavelengths longer than 400nm, e.g., blue, green, yellow, orange or red

where:

-   -   n is an integer of 3 to 8;    -   Z is O, NR or S;    -   R′ is hydrogen; alkyl of from 1 to 24 carbon atoms, for example,        propyl, t-butyl, heptyl, and the like; aryl or        heteroatom-substituted aryl of from 5 to 20 carbon atoms for        example phenyl, naphthyl, furyl, thienyl, pyridyl, quinolinyl        and other heterocyclic systems; or halo such as chloro, fluoro;        or atoms necessary to complete a fused aromatic ring; and

L is a linkage unit including alkyl, aryl, substituted alkyl, orsubstituted aryl, which conjugately or unconjugately connects themultiple benzazoles together.

An example of a useful benzazole is2,2′,2″-(1,3,5-phenylene)-tris[1-phenyl-1H-benzimidazole].

Certain of the hole-transporting materials described above, e.g.4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl and4,4′-bis[N-(2-naphthyl)-N-phenylamino]biphenyl, can also be useful hostsfor one or more of the light-emitting layers of this invention.

Also useful as co-hosts in certain light-emitting layers of thisinvention are derivatives of tetracene, which will be seen to beparticularly useful in the red light-emitting layer of this invention

wherein R₁-R₆ represent one or more substituents on each ring and whereeach substituent is individually selected from one of the following:

-   -   Category 1: hydrogen, or alkyl of from 1 to 24 carbon atoms;    -   Category 2: aryl or substituted aryl of from 5 to 20 carbon        atoms;    -   Category 3: hydrocarbon containing 4 to 24 carbon atoms,        completing a fused aromatic ring or ring system;    -   Category 4: heteroaryl or substituted heteroaryl of from 5 to 24        carbon atoms such as thiazolyl, furyl, thienyl, pyridyl,        quinolinyl or other heterocyclic systems, which are bonded via a        single bond, or complete a fused heteroaromatic ring system;    -   Category 5: alkoxylamino, alkylamino, or arylamino of from 1 to        24 carbon atoms; or    -   Category 6: fluoro, chloro, bromo or cyano.

Suitable host materials for phosphorescent emitters (including materialsthat emit from a triplet excited state, i.e. so-called “tripletemitters”) should be selected so that the triplet exciton can betransferred efficiently from the host material to the phosphorescentmaterial. For this transfer to occur, it is a highly desirable conditionthat the excited state energy of the phosphorescent material be lowerthan the difference in energy between the lowest triplet state and theground state of the host. However, the band gap of the host should notbe chosen so large as to cause an unacceptable increase in the drivevoltage of the OLED. Suitable host materials are described in WO00/70655 A2; 01/39234 A2; 01/93642 A1; 02/074015 A2; 02/15645 A1, andU.S. Patent Application Publication 2002/0117662 A1. Suitable hostsinclude certain aryl amines, triazoles, indoles and carbazole compounds.Examples of desirable hosts are 4,4′-N,N′-dicarbazole-biphenyl (CBP),2,2′-dimethyl-4,4′-(N,N′-dicarbazole)biphenyl,m-(N,N′-dicarbazole)benzene, and poly(N-vinylcarbazole), including theirderivatives.

Desirable host materials are capable of forming a continuous film. Thelight-emitting layer can contain more than one host material in order toimprove the device's film morphology, electrical properties, lightemission efficiency, and lifetime. The light-emitting layer can containa first host material that has good hole-transporting properties, and asecond host material that has good electron-transporting properties.

In addition to suitable hosts, an OLED device employing a phosphorescentmaterial often requires at least one exciton- or hole-blocking layer tohelp confine the excitons or electron-hole recombination centers to thelight-emitting layer comprising the host and phosphorescent material. Inone embodiment, such a blocking layer would be placed between aphosphorescent light-emitting layer and the cathode, and in contact withthe phosphorescent light-emitting layer. In this case, the ionizationpotential of the blocking layer should be such that there is an energybarrier for hole migration from the host into the electron-transportinglayer (or the metal-doped organic layer), while the electron affinityshould be such that electrons pass more readily from theelectron-transporting layer (or the metal-doped organic layer) into thelight-emitting layer comprising host and phosphorescent material. It isfurther desired, but not absolutely required, that the triplet energy ofthe blocking material be greater than that of the phosphorescentmaterial. Suitable hole-blocking materials are described in WO00/70655A2 and WO 01/93642 A1. Two examples of useful materials arebathocuproine (BCP) andbis(2-methyl-8-quinolinolato)(4-phenylphenolato)-Aluminum(III)(BAlQ).Metal complexes other than Balq are also known to block holes andexcitons as described in U.S. Patent Application Publication2003/0068528 A1. U.S. Patent Application Publication 2003/0175553 A1describes the use of fac-tris(1-phenylpyrazolato-N,C²)iridium(III)(Irppz) in an electron/exciton blocking layer.

Certain red-, green-, and blue-light-emitting materials can beparticularly useful for this invention. Prior art displays which emitwhite light have included emitting layers that produce a broad range ofemitted wavelengths, e.g. EP 1 187 235 A2, which teaches a whitelight-emitting organic electroluminescent element with a substantiallycontinuous spectrum in the visible region of the spectrum. Otherexamples are described in, for example EP 1 187 235, U.S. 2002/0025419,EP 1 182 244, U.S. Pat. Nos. 5,683,823, 5,503,910, 5,405,709, and5,283,182. These will be referred to herein as broadband white emittersor broadband emitters. In contrast, it has been found that alight-emitting layer (or series of layers) with several narrowwell-defined maxima in the spectrum can be particularly useful whencombined with a series of microcavity structures.

For this invention, it has been found useful that a red light-emittingcompound have an emission maximum between 560 nm and 700 nm, and a fullwidth at half maximum of between 5 nm and 90 nm contained within thewavelength range of 560 nm and 700 nm. It is preferable that the redlight-emitting compound have a full width at half maximum of between 5nm and 40 nm contained within the wavelength range of 575 nm and 640 nm.The red light-emitting compound can include a diindenoperylene compoundof the following structure:

wherein X₁-X₁₆ are independently selected as hydrogen or substituentsthat include alkyl groups of from 1 to 24 carbon atoms; aryl orsubstituted aryl groups of from 5 to 20 carbon atoms; hydrocarbon groupscontaining 4 to 24 carbon atoms that complete one or more fused aromaticrings or ring systems; or halogen, provided that the substituents areselected to provide a full width at half maximum of between 5 nm and 90nm contained within the wavelength range of 560 nm and 700 nm.

Illustrative examples of useful red dopants of this class include thefollowing:

A particularly preferred diindenoperylene dopant is TPDBP (above).

It has been found useful that a green-light-emitting compound have anemission maximum between 500 and 540 nm, and a full width at halfmaximum of between 5 nm and 70 nm contained within the wavelength rangeof 490 nm and 580 nm. It is preferable that the green-light-emittingcompound have a full width at half maximum of between 5 nm and 40 nmcontained within the wavelength range of 500 nm and 540 nm. Thegreen-light-emitting compound can include a quinacridone compound of thefollowing structure:

wherein:

-   -   substituent groups R₁ and R₂ are independently alkyl, alkoxyl,        aryl, or heteroaryl; and    -   substituent groups R₃ through R₁₂ are independently hydrogen,        alkyl, alkoxyl, halogen, aryl, or heteroaryl, and adjacent        substituent groups R₃ through R₁₀ can optionally be connected to        form one or more ring systems, including fused aromatic and        fused heteroaromatic rings, provided that the substituents are        selected to provide a full width at half maximum of between 5 nm        and 70 nm contained within the wavelength range of 490 nm and        580 nm. Alkyl, alkoxyl, aryl, heteroaryl, fused aromatic ring        and fused heteroaromatic ring substituent groups can be further        substituted. Conveniently, R₁ and R₂ are aryl, and R₂ through        R₁₂ are hydrogen, or substituent groups that are more electron        withdrawing than methyl. Some examples of useful quinacridones        include those disclosed in U.S. Pat. No. 5,593,788 and in U.S.        Patent Application Publication 2004/0001969 A1.

Examples of useful quinacridone green dopants include:

The green-light-emitting compound can include a coumarin compound of thefollowing structure:

wherein X is O or S, R¹, R², R³ and R⁶ can individually be hydrogen,alkyl, or aryl; and

-   -   R⁴ and R⁵ can individually be alkyl or aryl, or where either R³        and R⁴, or R⁵ and R⁶, or both together represent the atoms        completing a cycloalkyl group, provided that the substituents        are selected to provide a full width at half maximum of between        5 nm and 70 nm contained within the wavelength range of 490 nm        and 580 nm.

Examples of useful coumarin green dopants include:

It has been found useful that a blue-light-emitting compound have anemission maximum between 400 nm and 490 nm, and a full width at halfmaximum of between 5 nm and 25 nm contained within the wavelength rangeof 400 nm and 490 nm. The blue-light-emitting compound can include abis(azinyl)azene boron complex compound of the structure:

wherein:

-   -   A and A′ represent independent azine ring systems corresponding        to 6-membered aromatic ring systems containing at least one        nitrogen;    -   (X^(a))_(n) and (X^(b))_(m) represent one or more independently        selected substituents and include acyclic substituents or are        joined to form a ring fused to A or A′;    -   m and n are independently 0 to 4;    -   Z^(a) and Z^(b) are independently selected substituents;    -   1, 2, 3, 4, 1′, 2′, 3′, and 4′ are independently selected as        either carbon or nitrogen atoms; and    -   provided that X^(a), X^(b), Z^(a), and Z^(b), 1, 2, 3, 4, 1′,        2′, 3′, and 4′ are selected to provide a full width at half        maximum of between 5 nm and 25 nm contained within a wavelength        range of 400 nm and 490 nm.

Some examples of the above class of dopants include the following:

The light-emitting layer can comprise various stabilizing materials.Such materials are coated along with the host material, but at loweramounts and often have an energy bandgap between that of the primaryhost and that of the light-emitting dopant material. Some examples ofstabilizing materials include perylenes including dibenzoperylene anddiaryltetracenes, including tBuDPN, shown below

While not always necessary, it is often useful that microcavity pixel 10includes an electron-transporting layer 60 disposed over light-emittinglayers 45, 50, and 55. Desired electron-transporting materials can bedeposited by any suitable way such as evaporation, sputtering, chemicalvapor deposition, electrochemical means, thermal transfer, or laserthermal transfer from a donor material. Preferred electron-transportingmaterials for use in electron-transporting layer 60 are metal chelatedoxinoid compounds, including chelates of oxine itself, also commonlyreferred to as 8-quinolinol or 8-hydroxyquinoline. Such compounds helpto inject and transport electrons and exhibit both high levels ofperformance and are readily fabricated in the form of thin films.Exemplary of contemplated oxinoid compounds are those satisfyingstructural Formula E, previously described.

Other electron-transporting materials include various butadienederivatives as disclosed in U.S. Pat. No. 4,356,429 and variousheterocyclic optical brighteners as described in U.S. Pat. No.4,539,507. Benzazoles satisfying structural Formula G are also usefulelectron-transporting materials. Related materials, denoted collectivelyas BAlq, can also be used as electron transporting materials. Bryan etal., in U.S. Pat. No. 5,141,671, discuss such materials. The BAlqcompounds are mixed-ligand aluminum chelates, specificallybis(R_(s)-8-quinolinolato)(phenolato)aluminum(III) chelates, where R_(s)is a ring substituent of the 8-quinolinolato ring nucleus. Thesecompounds are represented by the formula (R_(s)Q)₂AlOL, where Qrepresents a substituted 8-quinolinolato ligand, R_(s) represents an8-quinolinolato ring substituent to block sterically the attachment ofmore than two substituted 8-quinolinolato ligands to the aluminum ion,OL is phenolato ligand, O is oxygen, and L is phenyl or ahydrocarbon-substituted phenyl moiety of from 6 to 24 carbon atoms.These materials also make good hole- or exciton-blocking layers for usewith triplet emitting materials, as is known in the art.

Other electron-transporting materials can be polymeric substances, e.g.polyphenylenevinylene derivatives, poly-para-phenylene derivatives,polyfluorene derivatives, polythiophenes, polyacetylenes, and otherconductive polymeric organic materials such as those listed in Handbookof Conductive Molecules and Polymers, Vols. 1-4, H. S. Nalwa, ed., JohnWiley and Sons, Chichester (1997).

It will be understood that, as is common in the art, some of the layerscan have more than one function. For example, light-emitting layers 45,50, or 55 can have hole-transporting properties or electron-transportingproperties as desired for performance of the OLED device.Hole-transporting layer 40 or electron-transporting layer 60, or both,can also have emitting properties. In such a case, fewer layers thandescribed above can be sufficient for the desired emissive properties,so long as three layers have the light-emitting qualities as describedherein.

The organic EL media materials mentioned above are suitably depositedthrough a vapor-phase method including sublimation, sputtering, chemicalvapor deposition, and thermal transfer from a donor element. Organic ELmedia materials can alternatively be deposited from a fluid, forexample, from a solvent with an optional binder to improve filmformation. Deposition from a fluid can be done in many ways including,but not limited to ink-jet, spin coating, curtain coating, spraycoating, and electrochemical deposition. If the material is a polymer,solvent deposition is usually preferred, but other methods can be used,including sputtering, electrochemical deposition, electrophoreticdeposition or thermal transfer from a donor sheet. The material to bedeposited by sublimation can be vaporized from a sublimation “boat”often comprised of a tantalum material, e.g., as described in U.S. Pat.No. 6,237,529, or can be first coated onto a donor sheet and thensublimed in closer proximity to the substrate. Layers with a mixture ofmaterials can utilize separate sublimation boats or the materials can bepremixed and coated from a single boat or donor sheet.

An electron-injecting layer 65 can also be present between the cathodeand the electron-transporting layer. Examples of electron-injectingmaterials include alkaline or alkaline earth metals, alkali halidesalts, such as LiF mentioned above, or alkaline or alkaline earth metaldoped organic layers.

The second electrode, if part of an active matrix display configuration,can be a single electrode for all pixels of the display. Alternatively,the second electrode can be part of a passive matrix display, in whicheach second electrode can activate a column of pixels, and the secondelectrodes are arranged orthogonal to anodes.

Cathode materials can be deposited by evaporation, sputtering, orchemical vapor deposition. When needed, patterning can be achievedthrough many well known methods including, but not limited to,through-mask deposition, integral shadow masking as described in U.S.Pat. No. 5,276,380 and EP 0 732 868, laser ablation, and selectivechemical vapor deposition.

Although not shown, microcavity pixel 10 can also include a colorfilter, which includes color filter elements for the color to be emittedfrom microcavity pixel 10. The color filter is constructed to pass apreselected color of light, so as to produce a preselected color output.An array of three different kinds of color filters that pass red, green,and blue light, respectively, is particularly useful in a full colorOLED device. Several types of color filters are known in the art. Acolor filter array can be disposed in operative association with one ormore of the array of light-emitting microcavity pixels, and can beformed on, in, or spaced from the OLED display. In a top-emittingconfiguration, the color filter can be formed on a second transparentsubstrate and then aligned with the pixels of the first substrate 20. Analternative type of color filter can be formed directly over theelements of a pixel. In a display comprising multiple pixels, the spacebetween the individual color filter elements can also be filled with ablack matrix to reduce pixel cross talk and improve the display'scontrast. Alternatively, the color filters can be replaced with colorchange media (CCM). A color change medium absorbs light of onewavelength and emits light of a longer wavelength by fluorescence.Commonly, a CCM layer absorbs blue or green light and emits green orred. CCM layers can be used in conjunction with color filters.

The contrast of the display can be improved using a polarizing layer, inparticular, by using a circular polarizer as is well known in the art.

Several microcavity structures are known in the art. An example of anOLED microcavity device with a thin metallic layer as thesemitransparent reflector is discussed in N. Takada, T. Tsutsui, S.Saito, Appl. Phy. Lett, 63 (15), 2032-2034 (1993). Microcavity devicestend to have narrow and intense spectral emission when viewed at thenormal (0 degree) viewing angle. This effect can be used to produce fullcolor devices from a single broad spectrum emitting OLED medium such asshown in U.S. Pat. No. 5,554,911. However, as the viewing angle from thenormal is increased, the spectral emission tends to shift toward lowerwavelengths as illustrated in U.S. Pat. No. 5,780,174. For a green tunedmicrocavity, it is meant the perceived color would shift from green toblue at high angles. By incorporating a color filter element whichabsorbs light at lower wavelengths, the apparent change in color can besuppressed.

In a microcavity device, the light-reflective structure andsemitransparent structure (e.g., reflector 90 and semitransparentreflector 25) function, with the layers between them, to form amicrocavity structure. The strong optical interference in this structureresults in a resonance condition wherein emission near the resonancewavelength is enhanced and emission away from the resonance wavelengthis depressed. The optical path can be adjusted in thickness andrefractive index to resonate at a desired wavelength. Examples ofmicrocavity structures are shown in U.S. Pat. Nos. 6,406,801, 5,780,174,and JP 11288786. Microcavity pixel 10 can include cavity spacer layer 30as an additional way to adjust the microcavity structure resonancewavelength. Cavity spacer layer 30 can comprise e.g. a transparentconductive material, such as indium-tin oxide (ITO). Light that isemitted on-axis includes one or more narrow wavelength bands of light.That is, the microcavity structure enhances on-axis light produced fromlight-emitting layers 45, 50, and 55 in at least one particularwavelength to produce a desired on-axis viewed color while notsubstantially enhancing other wavelengths of such light.

The thickness of the microcavity structure including cavity spacer layer30 (if present) is selected to tune microcavity pixel 10 to have theresonance at the predetermined wavelength to be emitted from the device.The thickness satisfies the following equation:2Σn _(i) L _(i)+2n _(s) L _(s)+(Q _(m1) +Q _(m2))λ/2π=mλ  Eq. 1wherein:

-   -   n_(i) is the refractive index and L_(i) is the thickness of the        ith sub-layer in the microcavity structure of microcavity pixel        10;    -   n_(s) is the refractive index and L_(s) is the thickness, which        can be zero, of the cavity spacer layer 30;    -   Q_(m1) and Q_(m2) are the phase shifts in radians at the two        organic EL element-reflector interfaces, respectively;    -   λ is the predetermined wavelength of on-axis light to be        enhanced by the microcavity structure; and    -   m is a non-negative integer.        For example, one can select the microcavity effect to enhance        on-axis the emission of green light for a desired on-axis viewed        color.

Most OLED devices are sensitive to moisture or oxygen, or both, so theyare commonly sealed in an inert atmosphere such as nitrogen or argon,along with a desiccant such as alumina, bauxite, calcium sulfate, clays,silica gel, zeolites, alkaline metal oxides, alkaline earth metaloxides, sulfates, or metal halides and perchlorates. Methods forencapsulation and desiccation include, but are not limited to, thosedescribed in U.S. Pat. Nos. 6,226,890 and 6,656,609.

In addition, inorganic and/or organic barrier layers can be coated overthe OLED to provide improved sealing against moisture penetration.Alternating layers of inorganic and organic barrier layers areparticularly useful.

Some examples of inorganic barrier layer materials include dielectricssuch as aluminum oxide, silicon dioxide, silicon nitride, siliconoxynitride, indium-tin oxide, diamond-like carbon, and compositematerials such as, for example, zinc sulfide:silicon dioxide. Suchinorganic dielectric materials can form inorganic dielectric layers bycondensing from the vapor phase in deposition processes which includethermal physical vapor deposition, sputter deposition, chemical vapordeposition, plasma-enhanced chemical vapor deposition, laser-inducedchemical vapor deposition, induction-assisted chemical vapor deposition,electron-beam assisted vapor deposition, and atomic layer depositionprocesses.

In some cases, the inorganic barrier layer can include conductivemetals. Examples of metals from which a metal layer can be formed bydeposition from a vapor phase include, but are not limited to, aluminum,gold, silver, tantalum nitride, titanium nitride, and tungsten. Thesecan be deposited by sputter deposition, vapor deposition, or othermethods known in the art.

Organic barrier layers can include polymeric or small molecule organicmaterials. Preferred polymer materials for forming an organic barrierlayer include parylene materials, which can be deposited from a vaporphase to provide a polymer layer having a relatively small number ofdefects, excellent adhesion to, and step coverage over, topologicalfeatures of the OLED devices.

Turning now to FIG. 2, there is shown a cross-sectional view of a colorOLED display 15 according to this invention. Color OLED display 15comprises an array of three different colored light-emitting microcavitypixels, e.g. microcavity pixels 10 a, 10 b, and 10 c, wherein first,second, and third light-emitting layers 45, 50, and 55, respectively,are common for all different colored pixels. Each pixel has its ownanode, which is capable of independently causing emission of theindividual pixel. Pixel 10 a further includes semitransparent reflector25 a and cavity spacer layer 30 a. Pixel 10 b further includessemitransparent reflector 25 b and cavity spacer layer 30 b. Pixel 10 cfurther includes semitransparent reflector 25 c. Semitransparentreflectors 25 a, 25 b, and 25 c are preferably a thin transparent metalsuch as Ag or an alloy of Ag and is preferably between 5 nm and 35 nm inthickness. Because semitransparent reflectors 25 a, 25 b, and 25 c areconductive, they need to be electrically isolated to permit each pixelto be driven independently. If a non-conductive material was chosen toserve the function of the semitransparent reflector, such as is the casefor a quarter wave stack (QWS), then the semitransparent reflector canbe configured to be common for all pixels. Cavity spacer layers 30 a and30 b are preferably a transparent conductive material such as indium tinoxide (ITO) or the like. In this case, cavity spacer layers 30 a and 30b serve the function of the first electrode or anode and therefore mustalso be electrically isolated from the other pixels. Pixel 10 c isarranged so as to not need a cavity spacer layer, so that for pixel 10c, semitransparent reflector 25 c is designed to serve the function ofthe first electrode or anode. This arrangement is preferable, in orderto limit the number of patterning steps required to produce the cavityspacer layers. Alternately, in other embodiments, pixel 10 c could alsobe supplied with a cavity spacer layer.

Each different colored microcavity pixel 10 a, 10 b, and 10 c is tunedto produce light in one of the three different colors produced bylight-emitting layers 45, 50, and 55 so that the first, second, andthird different colors are produced by color OLED display 15. Forexample, the thickness and refractive index of the microcavity structureof pixel 10 a, including cavity spacer layer 30 a, can be selected totune the microcavity of pixel 10 a to produce light of a first color ofthe array, which is the color produced by first light-emitting layer 45,e.g., red. Similarly, microcavity pixel 10 b with cavity spacer layer 30b can be tuned to produce light of a second color of the array, which isthe color produced by second light-emitting layer 50, e.g., green.Microcavity pixel 10 c can be tuned to produce light of a third color ofthe array, which is the color produced by third light-emitting layer 55,e.g., blue. In this preferred embodiment, in order to reduce patterningsteps, the thickness and refractive index of the organic EL element 70is preferably tuned to be optimal for pixel 10 c such that pixel 10 cdoes not require a cavity spacer layer. The organic EL element 70 isthen deposited without the need for precision shadow masking betweenpixels. Cavity spacer layers 30 a and 30 b are then separately adjustedto tune the microcavities of pixels 10 a and 10 b respectively. Thus,each pixel 10 a, 10 b, and 10 c in color OLED display 15 forms a tunedmicrocavity OLED device. Such a microcavity device has emission outputefficiency above that of a comparable OLED device that is constructedwithout a microcavity. Thus, three different colors can be produced by acolor OLED display 15 which includes common first, second, and thirdlight-emitting layers 45, 50, and 55, respectively.

An alternative embodiment of color OLED display 15 is possible that doesnot include cavity spacer layers. Instead, the thickness of at least oneof the organic layers other than the light-emitting layers, e.g.hole-transporting layer 40 or electron-transporting layer 60, can bechanged for each different colored pixel so as to tune the microcavityto produce the desired color of light.

Color OLED display 15 can further include a color filter array asdescribed above. The color filter array filters light corresponding toportions of the array, pixels 10 a, 10 b, and 10 c, corresponding to thedifferent color portions, e.g. the red, green, and blue portions.

The invention and its advantages can be better appreciated by thefollowing comparative examples.

EXAMPLE 1 (COMPARATIVE)

A comparative color OLED display was constructed in the followingmanner:

-   -   1. A clean glass substrate was deposited by sputtering with        indium tin oxide (ITO) to form a transparent electrode of 85 nm        thickness;    -   2. The above-prepared ITO surface was treated with a plasma        oxygen etch, followed by plasma deposition of a 0.1 nm layer of        a fluorocarbon polymer (CFx) as described in U.S. Pat. No.        6,208,075;    -   3. The above-prepared substrate was further treated by        vacuum-depositing a 170 nm layer of        4,4′-bis[N-(1-naphthyl)-N-phenylamino]biphenyl (NPB) as a        hole-transporting layer (HTL);    -   4. A 30 nm layer of 24 nm NPB and 6 nm        5,12-bis(t-butylphenyl)naphthacene (tBuDPN) containing 3%        6,11-diphenyl-5,12-bis(4-(6-methyl-benzothiazol-2-yl)phenyl)naphthacene        (DBzR) was vacuum-deposited onto the substrate at a coating        station that included a heated graphite boat source to form a        yellow-light-emitting layer (yellow LEL);    -   5. A coating of 37 nm of        2-tert-butyl-9,10-bis(2-naphthyl)anthracene (TBADN) with 3 nm        NPB and 2.5%        4-(di-p-tolylamino)-4′-[(di-p-tolylamino)styryl]stilbene (TPDBP        above) was evaporatively deposited on the above substrate to        form a blue-light-emitting layer (blue LEL);    -   6. A 10 nm electron-transporting layer (ETL) of        tris(8-quinolinolato)aluminum (III) (ALQ) was vacuum-deposited        onto the substrate at a coating station that included a heated        tantalum boat source; and    -   7. A 0.5 nm layer of lithium fluoride was evaporatively        deposited onto the substrate, followed by a 100 nm layer of        aluminum, to form a cathode layer.

EXAMPLE 2 (INVENTIVE)

An inventive color OLED display was constructed in the following manner:

-   -   1. A clean glass substrate was deposited by sputtering with        indium tin oxide (ITO) to form a transparent electrode of 85 nm        thickness;    -   2. The above-prepared ITO surface was treated with a plasma        oxygen etch, followed by plasma deposition of a 0.1 nm layer of        a fluorocarbon polymer (CFx) as described in U.S. Pat. No.        6,208,075;    -   3. The above-prepared substrate was further treated by        vacuum-depositing a 240 nm layer of NPB as a hole-transporting        layer (HTL);    -   4. A 28 nm layer of 20 nm NPB and 8 nm rubrene containing 0.5%        TPDPB (above) was vacuum-deposited onto the substrate at a        coating station that included a heated graphite boat source to        form a red light-emitting layer (red LEL);    -   5. A coating of 20 nm of        2-tert-butyl-9,10-bis(2-naphthyl)anthracene (TBADN) with 1 nm        NPB and 0.75% BEP (above) was evaporatively deposited on the        above substrate to form a blue-light-emitting layer (blue LEL);    -   6. A 15 nm layer of ALQ containing 0.5% diphenylquinacridone        (DPQA) was evaporatively deposited on the above substrate to        form a green light-emitting layer (green LEL);    -   7. A 15 nm electron-transporting layer (ETL) of ALQ was        vacuum-deposited onto the substrate at a coating station that        included a heated graphite boat source; and    -   8. A 0.5 nm layer of lithium fluoride was evaporatively        deposited onto the substrate, followed by a 100 nm layer of        aluminum, to form a cathode layer.

EXAMPLE 3 (INVENTIVE)

An inventive color OLED display was constructed in the manner describedin Example 2, except the following steps were changed:

-   -   4. A 27 nm layer of 20 nm NPB and 7 nm rubrene containing 0.5%        TPDPB (above) was vacuum-deposited onto the substrate at a        coating station that included a heated graphite boat source to        form a red light-emitting layer (red LEL);    -   5. A coating of 40 nm of TBADN with 0.5% DPQA was evaporatively        deposited on the above substrate to form a green-light-emitting        layer (green LEL);    -   6. A coating of 20 nm of TBADN with 1 nm NPB and 0.75% BEP was        evaporatively deposited on the above substrate to form a        blue-light-emitting layer (blue LEL); and    -   7. A 20 nm electron-transporting layer (ETL) of ALQ was        vacuum-deposited onto the substrate at a coating station that        included a heated graphite boat source.

EXAMPLE 4 (INVENTIVE)

An inventive color OLED display was constructed in the manner describedin Example 2, except that the following steps were changed:

-   -   3. The above-prepared substrate was further treated by        vacuum-depositing a 120 nm layer of NPB as a hole-transporting        layer (HTL);    -   4. A 27 nm layer of 20 nm NPB and 7 nm rubrene containing 0.5%        TPDPB (above) was vacuum-deposited onto the substrate at a        coating station that included a heated graphite boat source to        form a red light-emitting layer (red LEL);    -   5. A coating of 10 nm of TBADN and 10 nm ALQ with 0.5% DPQA was        evaporatively deposited on the above substrate to form a        green-light-emitting layer (green LEL);    -   6. A coating of 20 nm of TBADN with 1 nm NPB and 0.75% BEP was        evaporatively deposited on the above substrate to form a        blue-light-emitting layer (blue LEL); and    -   7. A 20 nm electron-transporting layer (ETL) of ALQ was        vacuum-deposited onto the substrate at a coating station that        included a heated graphite boat source.

The devices were tested by applying a current across the electrodes of20 mA/cm² and measuring the emission spectrum. These spectra are shownin FIGS. 3 a, 4 a, 5 a, and 6 a for examples 1 to 4, respectively. Theλ_(max) 105 is one wavelength of maximum emission, e.g. 472 nm, in FIG.3 a. Full width at half maximum 110 is defined as the width of a givenpeak at one-half its maximum value. For example, the blue peak in FIG. 3a has a radiance maximum of 0.57 (λ_(max) 105). The width of this peakat radiance 0.28 (full width at half maximum 110) is 60 nm(approximately 460 to 520 nm). The relative luminous efficiency isdefined as the luminous efficiency of the example device, in cd/A,divided by the luminous efficiency in, cd/A, of reference Example 1. Therelative power consumption is defined as the power consumption of theexample device, in watts (W), divided by the power consumption, in W, ofreference Example 1. The power consumption was calculated, in W, for afull color display showing D65 white at 120 cd/m2. For lifetime, theintensity was monitored as a function of time at a constant current of80 ma/cm². The relative lifetime is defined as the time tohalf-luminance intensity of the example device, in hours, divided by thetime to half-luminance intensity of the reference comparative example.Table 1 below shows the results. TABLE 1 Example 1 Example 2 Example 3Example 4 (Comparative) (Inventive) (Inventive) (Inventive) Red dopant —0.5% TPDPB 0.5% TPDPB 0.5% TPDPB Yellow dopant 3% DBzR — — — Greendopant — 0.5% DPQA 0.5% DPQA 0.5% DPQA Green host — ALQ TBADN TBADN/ALQBlue dopant 2.5% L47 0.75% BEP 0.75% BEP 0.75% BEP Emitting layer order(bottom to top) YB RBG RGB RGB Relative White Luminous Efficiency 1 0.540.72 0.63 Relative lifetime 1 4.5 3.5 3.0 Relative Power Consumption 11.73 1.19 1.19 Red λ_(max) 572 nm 604 nm 608 nm 608 nm Red full width athalf maximum 84 nm 28 nm 28 nm 28 nm Red FWHM Range 546-630 nm 592-620nm 592-620 nm 592-620 nm Green λ_(max) — 508 nm 516 nm 520 nm Green fullwidth at half maximum — 32 nm 28 nm 28 nm Green FWHM Range — 511-543 nm504-532 nm 507-535 nm Blue λ_(max) 472 nm 452 nm 452 nm 452 nm Blue fullwidth at half maximum 60 nm 12 nm 12 nm 12 nm Blue FWHM Range 460-520 nm446-458 nm 446-458 nm 446-458 nm

The above examples were constructed in a non-microcavity architecture,which does not contain a reflective semitransparent structure, so as toobtain the full emission spectrum of the white OLED. The properties ofthe example devices above were then modeled in a microcavity devicecomprising a reflective semitransparent structure. Theelectroluminescence (EL) spectrum produced by a given device ispredicted using an optical model that solves Maxwell's Equations foremitting dipoles of random orientation in a planar multilayer device (O.H. Crawford, J. Chem. Phys. 89, p6017, 1988; K. B. Kahen, Appl. Phys.Lett. 78, p1649, 2001). The innate spectrum of the dipole emitters isdetermined (“back-derived”) from the EL spectrum of each of thecomparative and inventive example devices above. This innate spectrum,along with the optical response of the microcavity device structure, isthen used to predict the EL spectrum of the microcavity devices. For thepurposes of the model, this emission is assumed to occur uniformly inthe first 10 nm of the second emitting-layer in a two- or three-emitterlayer structure. For each layer, the model uses wavelength-dependentcomplex refractive indices that are either measured by spectroscopicellipsometry or taken from the literature (Handbook of Optical Constantsof Solids, ed. by E. D. Palik, Academic Press, 1985; Handbook of OpticalConstants of Solids II, ed. by E. D. Palik, Academic Press, 1991; CRCHandbook of Chemistry and Physics, 83rd ed., edited by D. R. Lide, CRCPress, Boca Raton, 2002). Once the EL spectrum has been derived, it isstraightforward to compute the luminance (up to a constant factor) andthe CIE chromaticities of this spectrum. Numerous comparisons betweenpredicted EL spectra and measured EL spectra have confirmed that themodel predictions are very accurate. This permitted calculation of the1931 CIE x,y-chromaticity diagram coordinates and luminous efficiency,in cd/A, for red-, green-, and blue-tuned microcavity pixels throughrepresentative red, green, and blue color filters, as well as thecomposite white coordinates and luminance, at viewing angles from 0° to60°. The red, green, and blue coordinates at 0° viewing angle are shownin FIG. 3 b, 4 b, 5 b, and 6 b for examples 1 to 4, respectively, whichrepresent the color gamuts 115, 120, 125, and 130, respectively, of thedevices. The data for white is for a recombination of red, green, andblue light emitted through the microcavity structure and the appropriatecolor filter to make D65 white with 120 cd/m² luminance in the on-axisdirection. The results of modeling are also shown in Table 2 below.Relative luminous efficiency is defined as the luminous efficiency ofthe color in the example device divided by the luminous efficiency ofthat color in device Example 1. The CIEx,y change is calculated by thefollowing equation:Delta CIEx,y={square root}{square root over ([(CIEx _(0°) −CIEx_(60°))²+(CIEy _(0°) −CIEy _(60°))²])}.

TABLE 2 Example 1 Example 2 Example 3 Example 4 (Comparative)(Inventive) (Inventive) (Inventive) Red (CIEx, y) 0.623, 0.371 0.638,0.354 0.630, 0.339 0.635, 0.348 Red CIEx, y change at 60° viewing 0.060.07 0.09 0.08 angle Relative red luminous efficiency 1 0.56 0.45 0.67Red luminous efficiency loss at 60° 86% 90% 71% 87% viewing angle Green(CIEx, y) 0.329, 0.627 0.262, 0.690 0.157, 0.721 0.203, 0.713 GreenCIEx, y change at 60° viewing 0.21 0.16 0.25 0.16 angle Relative greenluminous efficiency 1 0.61 0.98 0.77 Green luminous efficiency loss at60° 66% 71% 72% 52% viewing angle Blue (CIEx, y) 0.120, 0.100 0.144,0.063 0.137, 0.077 0.144, 0.059 Blue CIEx, y change at 60° viewing 0.020.03 0.04 0.02 angle Relative blue luminous efficiency 1 0.35 0.93 0.58Blue luminous efficiency loss at 60° 71% 56% 46% 83% viewing angle White(CIEx, y) 0.355, 0.399 0.364, 0.369 0.260, 0.322 0.274, 0.336 WhiteCIEx, y change at 60° viewing 0.12 0.12 0.09 0.13 angle White luminanceloss at 60° viewing 73% 75% 72% 64% angle

These results show several advantages of this invention. FIGS. 4 b, 5 b,and 6 b show that, in comparison to Example 1 (FIG. 3 b), the inventionshows a larger color gamut. As shown in Table 1, the invention exhibitsa significant increase in device lifetime. The power consumption ishigher, but it is possible (as in Examples 3 and 4) to keep thisincrease relatively small while achieving the other significantbenefits. Table 2 shows that the change in color of the green pixels ata viewing angle of up to 60° off-axis can be significantly less than thecomparative example, as demonstrated in Examples 2 and 4. As is shown inTable 2, the white emitter can be chosen to reduce the loss of luminousefficiency off-angle for a particular color, in order to tailor thedevice for a given application, e.g. Example 4 for green and Examples 2and 3 for blue. Thus, although the on-axis luminous efficiency is lessfor devices of this invention, the perception of luminance variationwith angle will be less to the viewer.

The invention has been described in detail with particular reference tocertain preferred embodiments thereof, but it will be understood thatvariations and modifications can be effected within the spirit and scopeof the invention.

Parts List

-   10 microcavity pixel-   10 a microcavity pixel-   10 b micro cavity pixel-   10 c micro cavity pixel-   15 color OLED display-   20 substrate-   25 semitransparent reflector-   25 a semitransparent reflector-   25 b semitransparent reflector-   25 c semitransparent reflector-   30 cavity spacer layer-   30 a cavity spacer layer-   30 b cavity spacer layer-   35 hole-injecting layer-   40 hole-transporting layer-   45 first light-emitting layer-   50 second light-emitting layer-   55 third light-emitting layer-   60 electron-transporting layer-   65 electron-injecting layer-   70 organic EL element-   90 reflector-   105 λ_(max)-   110 full width at half maximum-   115 color gamut-   120 color gamut-   125 color gamut-   130 color gamut

1. A color OLED display having at least three different coloredmicrocavity pixels including a light-reflective structure and asemitransparent structure, comprising: a) an array of light-emittingmicrocavity pixels each having one or more common organic light-emittinglayers, said light-emitting layer(s) having first, second, and thirdlight-emitting materials that produce different light spectra, the firstlight-emitting material producing light having a first spectrum portionthat is substantially contained within a first color of the array, thesecond light-emitting material producing light having a second spectrumportion that is substantially contained within a second color that isdifferent from the first color, and the third light-emitting materialproducing light having a third spectrum portion that is substantiallycontained within a third color that is different from the first andsecond colors; and b) each different colored pixel being tuned toproduce light in one of the three different colors whereby the first,second, and third different colors are produced by the OLED display. 2.The color OLED display of claim 1 wherein the first, second, and thirdlight-emitting materials are contained in separate red, green, and bluelight-emitting layers, respectively, and wherein the red light-emittinglayer includes a first host and a red light-emitting compound, the greenlight-emitting layer includes a second host and a green-light-emittingcompound, and the blue light-emitting layer includes a third host and ablue-light-emitting compound.
 3. The color OLED display of claim 2wherein the blue light-emitting layer is disposed between the red andgreen light-emitting layers.
 4. The color OLED display of claim 2wherein the green light-emitting layer is disposed between the red andblue light-emitting layers.
 5. The color OLED display of claim 2 whereinthe second and third hosts are the same material.
 6. The color OLEDdisplay of claim 2 wherein the second host comprises a mixture of hostmaterials.
 7. The color OLED display of claim 2 wherein the third hostcomprises a mixture of host materials.
 8. The color OLED display ofclaim 2 wherein the red light-emitting compound has a full width at halfmaximum contained within the wavelength range of 560 nm and 700 nm. 9.The color OLED display of claim 8 wherein the red light-emittingcompound has a full width at half maximum of between 5 and 90 nm. 10.The color OLED display of claim 2 wherein the red light-emittingcompound is a diindenoperylene compound.
 11. The color OLED display ofclaim 10 wherein the diindenoperylene compound has the followingstructure

wherein X₁-X₁₆ are independently selected as hydrogen or substituentsthat include alkyl groups of from 1 to 24 carbon atoms; aryl orsubstituted aryl groups of from 5 to 20 carbon atoms; hydrocarbon groupscontaining 4 to 24 carbon atoms that complete one or more fused aromaticrings or ring systems; or halogen, provided that the substituents areselected to provide a full width at half maximum of 5 nm to 90 nmcontained within the wavelength range of 560 nm and 700 nm.
 12. Thecolor OLED display of claim 11 wherein the diindenoperylene compound is


13. The color OLED display of claim 2 wherein the green-light-emittingcompound has a full width at half maximum contained within thewavelength range of 490 nm and 580 nm.
 14. The color OLED display ofclaim 13 wherein the green light-emitting compound has a full width athalf maximum of between 5 and 70 nm.
 15. The color OLED display of claim2 wherein the green light-emitting compound is a quinacridone compound.16. The color OLED display of claim 15 wherein the quinacridone compoundhas the following structure:

wherein substituent groups R₁ and R₂ are independently alkyl, alkoxyl,aryl, or heteroaryl; and substituent groups R₃ through R₁₂ areindependently hydrogen, alkyl, alkoxyl, halogen, aryl, or heteroaryl,and adjacent substituent groups R₃ through R₁₀ can optionally beconnected to form one or more ring systems, including fused aromatic andfused heteroaromatic rings, provided that the substituents are selectedto provide a full width at half maximum of 5 nm to 70 nm containedwithin the wavelength range of 490 nm and 580 nm.
 17. The color OLEDdisplay of claim 16 wherein the quinacridone compound is


18. The color OLED display of claim 2 wherein the green light-emittingcompound is a coumarin compound.
 19. The color OLED display of claim 18wherein the coumarin compound has the following structure:

wherein X is O or S, R¹, R², R³, and R⁶ can individually be hydrogen,alkyl, or aryl, R⁴ and R⁵ can individually be alkyl or aryl, or whereeither R³ and R⁴, or R⁵ and R⁶, or both together represent the atomscompleting a cycloalkyl group, provided that the substituents areselected to provide a full width at half maximum of between 5 and 70 nmcontained within the wavelength range of 490 nm and 580 nm.
 20. Thecolor OLED display of claim 19 wherein the coumarin compound is


21. The color OLED display of claim 2 wherein the blue-light-emittingcompound has a full width at half maximum contained within thewavelength range of 400 nm and 490 nm.
 22. The color OLED display ofclaim 21 wherein the blue-light-emitting compound has a full width athalf maximum of between 5 and 25 nm.
 23. The color OLED display of claim2 wherein the blue light-emitting compound is a bis(azinyl)azene boroncomplex.
 24. The color OLED display of claim 23 wherein thebis(azinyl)azene boron complex has the following structure

wherein: A and A′ represent independent azine ring systems correspondingto 6-membered aromatic ring systems containing at least one nitrogen;(X^(a))_(n) and (X^(b))_(m) represent one or more independently selectedsubstituents and include acyclic substituents or are joined to form aring fused to A or A′; m and n are independently 0 to 4; Z^(a) and Z^(b)are independently selected substituents; 1, 2, 3, 4, 1′, 2′, 3′, and 4′are independently selected as either carbon or nitrogen atoms; andprovided that X^(a), X^(b), Z^(a), and Z^(b), 1, 2, 3, 4, 1′, 2′, 3′,and 4′ are selected to provide an a full width at half maximum ofbetween 5 and 25 nm contained within the wavelength range of 400 nm and490 nm.
 25. The color OLED display of claim 24 wherein thebis(azinyl)azene boron complex is


26. The OLED device of claim 1 where the reflector, the semitransparentreflector, or both, also serve as electrodes for the light-emittinglayers.
 27. The color OLED display of claim 1 wherein the material forreflector includes Ag, Au, Al, or alloys thereof.
 28. The color OLEDdisplay of claim 1 wherein the material for the semitransparentreflector includes Ag, Au, or alloys thereof.
 29. The color OLED displayof claim 1 wherein at least two of the different colored microcavitypixels further include a cavity spacer layer wherein the thickness ofthe cavity spacer layer is different for each of said different coloredmicrocavity pixels.
 30. The color OLED display of claim 2 wherein thesemitransparent reflector is disposed between the red, green, and bluelight-emitting layers and the substrate.
 31. The color OLED display ofclaim 1 wherein the reflector is disposed between the first, second, andthird light-emitting layers and the substrate.
 32. The color OLEDdisplay of claim 1 wherein the thickness of at least one of the organiclayers other than the light-emitting layers is changed for eachdifferent colored pixel.
 33. The color OLED display of claim 1 furtherincluding a color filter array disposed in operative association withone or more of the array of light-emitting microcavity pixels thatfilters light corresponding to the portions of the array correspondingto the red, green, and blue portions.
 34. The color OLED display ofclaim 2 wherein at least one of the hosts is an anthracene derivativehaving the following formula:

wherein: Ar is an (un)substituted condensed aromatic group of 10-50nuclear carbon atoms; Ar′ is an (un)substituted aromatic group of 6-50nuclear carbon atoms; X is an (un)substituted aromatic group of 6-50nuclear carbon atoms, (un)substituted aromatic heterocyclic group of5-50 nuclear carbon atoms, (un)substituted alkyl group of 1-50 carbonatoms, (un)substituted alkoxy group of 1-50 carbon atoms,(un)substituted aralkyl group of 6-50 carbon atoms, (un)substitutedaryloxy group of 5-50 nuclear carbon atoms, (un)substituted arylthiogroup of 5-50 nuclear carbon atoms, (un)substituted alkoxycarbonyl groupof 1-50 carbon atoms, carboxy group, halogen atom, cyano group, nitrogroup, or hydroxy group; a, b, and c are whole numbers of 0-4; n is awhole number of 1-3; and when n is 2 or more, the formula inside theparenthesis shown below can be the same or different:


35. The color OLED display of claim 34, wherein Ar in general formula(1) is selected from the general formulas given below:

wherein Ar₁ is an (un)substituted aromatic group of 6-50 nuclear carbonatoms.
 36. The color OLED display of claim 34 wherein the host isselected from: